The principal aim of the research program set forth in this application is to improve the methodology currently employed to synthesize compounds with physiological activity. In particular, the stereoselectivity (both enantioselectibility and regioselectivity) of common organic reactions is of major concern in the preparation of many of the compounds listed in the NCI publication Chemical Structures of Interest to the Division of Cancer Treatment. Since a number of the compounds on the current list of chemical compounds used in clinical trials or in earlier stages of development are prepared by; chemical synthesis, it is important that efficient and useful processes exist for the preparation of these compounds in vitro. The work outlined herein will greatly assist with the ongoing development of synthetic routes to a number of the compounds of interest to the National Cancer Institute. In addition, the total syntheses of non- naturally occurring analogy of these compounds may be more easily prepared by carefully consideration of the results of this research. In light of the increasing emphasis placed upon the search for enantiospecific organic reactions, a proposal to improve the efficiency of enantiospecific reactions is presented. This goal will be pursued by structural investigations, both by NMR and x- ray diffraction analyses, of the common reactive intermediates thought to be involved in the reactions. The structural information will be utilized to devise models to explain and to predict the stereoreactivity of the reactive intermediates. Additionally, the structural information obtained herein will be used to devise and to develop new synthetic reagents for asymmetric synthesis of organic molecules. The structural work will be followed up by experimental work on the development of new asymmetric reactions for use in the total synthesis of physiologically active compounds.